I moved a 1950 pier and beam house onto a new foundation. The perimeter beam is 12" wide which provides an approximately 6" masonry ledge on the outside of the house. The frame is covered with 3/4" planks covered with 1/8" cement shingles with felt between and no insulation. I want to place limestone on the ledge. What's the best way to do this? Can I lay the stone against the shingles or leave a gap? What do I need in the way of vapor barrier, ties ,flashing or whatever? Any advice would be welcome.